Disclosed herein is a vehicle seat flip-up mechanism and a vehicle seat with the vehicle seat flip-up mechanism, and particularly, a vehicle seat flip-up mechanism that may be stably fixed to a vehicle body floor and may stably stow a vehicle seat in a rotating manner, and a vehicle seat that includes the vehicle seat flip-up mechanism.
There is known a vehicle seat including a seat cushion which moves between a sitting position and a stowed position and a seat cushion driving mechanism which performs an operation (hereinafter, referred to as a seat cushion moving operation) for moving the seat cushion from the sitting position toward the stowed position. The cushion driving mechanism as a component of the vehicle seat is equipped with a movable member that is movable during the seat cushion moving operation (for example, see Japanese Patent Document 2011-11665 A 1 (“the '665 Document”)). The vehicle seat disclosed in the '665 Document is equipped with a support arm which is a movable member rotatably supported while the seat cushion is fixed to one end of the support arm.
Hitherto, as an example of the vehicle seat, a vehicle seat is known which may be stowed during non-use by inclining a seatback and flipping up a seat cushion. For example, Japanese Patent Document No. 4468310 B1 (“the '310 Document”) discloses a vehicle seat which may be stowed in a rotated state by inclining a seatback forward and flipping up a seat cushion forward.
In a double folding mechanism of the vehicle seat of the '310 Document, the seat cushion is mounted on a floor of a vehicle interior through a connection structure with a rotation mechanism. Then, in a case where the seat cushion is stowed, the seat cushion is rotated forward by the rotation mechanism with a pair of rotation members disposed while being separated from each other in the right and left direction and is held at a predetermined position.
In the connection structure, the pair of rotation members is connected by a connection shaft installed at the upper ends (that is, the ends mounted with the seat cushion). Then, each rotation member is biased by a spring member provided at the lower end of the rotation member, and when a locking state is canceled, the rotation member rotates by the biasing force of the spring member so that the seat cushion may be stowed.
In this way, in the vehicle seat which is stowed in a rotated state by flipping up the seat cushion, the rotation member is mounted on the seat cushion. In a case where the seat cushion is stowed, when the locking of the seat cushion is canceled, the seat cushion is flipped up to a stowed posture (a flip-up position) by the rotation mechanism. In a case where the seat cushion is returned to the sitting posture, an occupant rotates the seat cushion to a sitting position and fixes the position (the state) of the seat cushion by a lock mechanism so that the seat cushion may be disposed at the sitting position.
The connection structure of the double folding mechanism disclosed in the '310 Document is equipped with a plate-shaped fixing member that is fixed to a vehicle interior floor. Then, as the fixing member, a pair of fixing members having different shapes are installed in the seat width direction (the right and left direction), and a reinforcing member is installed in the fixing members. Accordingly, the connection structure is fixed to the vehicle interior floor through the plate-shaped fixing member that is substantially formed in an L-shape in the plan view.
In the vehicle seat which is stowed in a rotated state by flipping up the seat cushion, an elongated rotation member supporting the seat cushion in a rotatable manner is disposed along the front to back direction of the seat. Then, the rotation member needs to be formed with a predetermined length or more in order to flip up the seat cushion to the stowed posture (the flip-up position).
In the connection structure of the double folding mechanism disclosed in the '310 Document, the rotation member is formed to be longer than the fixing member. That is, when the seat cushion is held at the sitting posture, the rotation member protrudes rearward relative to the fixing member in the plan view.
As in the '310 Document, in the connection structure in which the fixing members are formed to not be symmetrical to each other in the right and left direction and the rotation member is formed in a large size, a problem arises that it is difficult to uniformly distribute a load applied to the seat cushion. Accordingly, the entire connection structure is easily inclined toward a position without the fixing member, and hence a problem arises that it is difficult to stably support the load of the occupant.
Further, in the connection structure of the double folding mechanism disclosed in the '310 Document, in a case where the seat cushion rotates, the rotation range of the seat cushion is defined by the rotation member. However, when the seat cushion does not stably rotate, an undesirable situation occurs in which the seat cushion is rotated to a non-locking position and hence may not be returned to the sitting posture or an undesirable situation occurs in which the seat cushion may not be rotated to an appropriate stowed posture. Accordingly, a technique has been demanded which may stably rotate the seat cushion and may stably hold the seat cushion in the sitting posture and the stowed posture at all times.
Further, in the double folding mechanism of the '310 Document, since plural components overlap one another in the seat width direction and the up to down direction in the seat cushion mounting structure, a problem arises that the size increase of the vehicle seat is facilitated.
Furthermore, when the seat cushion is located at the sitting position, the rotation member is located below the seat cushion and is covered by the seat cushion. However, when a part of the rotation member is exposed to the outside even while the rotation member is covered by the seat cushion, there is a concern that foreign substances such as trash or dust may adhere to the exposed portion. Further, when the seat cushion moves to the stowed position, the state of the rotation member changes from the state where the rotation member is covered by the seat cushion to the state where the rotation member is exposed to the outside. Thus, in such an exposed state, the foreign substance adhering phenomenon noticeably occurs.